Together with the safety benefits conferred by such airbags, there are also possible deleterious effects associated with their inflation and with variations in the size and position of the vehicle occupants, the sudden inflation of an airbag can produce so called "bag slap" whereby a part of the airbag travels further dynamically than its static fully inflated shape would suggest, and strikes the occupant at high speed. This occurs during the first 15 to 20 milli-seconds after crash impact, and before the airbag is fully inflated. In order to reduce the risk of "bag slap" a number of systems are currently in use. In one such system, permanent tethers or straps of webbing or fabric are formed between that part of the airbag which contacts the vehicle occupant and that part of the airbag having a throat hole for connection to the gas generator, hereinafter called the front part and the rear part of the airbag, so as to control the static shape of the airbag. In another such system, the front and rear parts of the airbag are sewn together by "tear seams" which fail when the airbag is inflated so as to alter its deployment characteristics and absorb some energy thereby reducing the speed of the front part of the airbag. The known tear seams comprise straight rows of stitching which absorb energy and restrain relative displacement of the front and rear parts of the airbag until they suddenly fail, whereupon relative displacement of said parts occurs without any further restraint. A passenger bag has both front and rear parts as well as sides, some or all of which may be joined together by the aforementioned tear seams.